The scientific core will be responsible for the in vivo studies with vaccines and cloned viruses in macaques using the well-established SIV:macaque model for AIDS. This core will provide access to the SIV:macaque model for evaluation of the novel vaccine strategies described. The clinical care and maintenance of all monkeys required for the subprojects, inoculations, immunizations, and sample collections will be performed by the veterinarian and/or project leader of this core. Monkey tissues will be provided for virus detection; sera from infected and/or immunized monkeys will be provided for analysis of humoral immune responses and virus neutralizing antibodies, respectively. Sera and cells will provide for measurements of cell mediated immunity. Peripheral blood lymphocytes will be provided for the generation of rhesus monoclonal antibodies. Following appropriate immunization, monkeys will be challenged either intravenously or mucosally with stock virus preparations (cell-free or cell-associated).